This document provides guidelines for designing user agents that lower barriers to Web
accessibility for people with disabilities. User agents include browsers and other types
of software that retrieve and render Web content. A user agent that
conforms to these guidelines will
promote accessibility through its own user interface and through other internal
facilities, including its ability to communicate with other technologies
(especially assistive technologies).
Furthermore, all users, not just users with disabilities, should find
conforming user agents to be more usable.

In addition to helping developers of browsers and media players, this
document will also benefit developers of assistive technologies because it
explains what types of information and control an assistive technology may
expect from a conforming user agent. Technologies not addressed directly by
this document (e.g., technologies for braille rendering) will be essential to
ensuring Web access for some users with disabilities.

The "User Agent Accessibility Guidelines 2.0" (UAAG 2.0)
is part of a series of accessibility guidelines published by the W3CWeb
Accessibility Initiative (WAI).

May be Superseded

This section describes the status of this document at the time of its
publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be
found in the W3C technical reports index at
http://www.w3.org/TR/.

W3C First Public Draft of UAAG 2.0

This is a First Public Working Draft of "UAAG 2.0". For more information, please see the UAAG 2.0 Requirements Document.
The Working Group expects for this document to become a
Working Group Note until such time as the group is recharted to produce
Recommendations under the W3C Patent Policy. At that point,
the group anticipates advancing it to W3C Recommendation
status.

Substantial changes since UAAG 1.0 include: (1) numerous clarifications and additions to the guidelines and success criteria as per the UAAG 2.0 Requirements Document, (2) restructuring the document into five principles similar to those used by WCAG 2.0 and ATAG 2.0, (3) adopting the three-priority level per guideline structure of WCAG 2.0 and ATAG 2.0, and (4) integrating the draft into a single document with streamlined introductory material.

The Working Group seeks feedback on the following points for this draft:

Is the new organization of this document clear and understandable?

Do these success criteria appear to cover the areas of greatest need with regard to browser and media player accessibility?

Based on these preliminary success criteria, are there any concerns about implementation feasibility?

Web Accessibility Initiative

No Endorsement

Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document specifies requirements that, if satisfied by
user agent developers, will lower barriers
to accessibility.

A separate document, entitled "Implementation Techniques for User Agent Accessibility
Guidelines 2.0" (the "Techniques document" from here on) will be produced at a later date. It will provide
suggestions and examples of how each success criteria might be satisfied. It also
includes references to other accessibility resources (such as platform-specific
software accessibility guidelines) that provide additional information on how a
user agent may satisfy each success criteria. The techniques in the Techniques
document are informative examples only,
and other strategies may be used or required to satisfy the success criteria. The
UAWG expects to update the Techniques document more
frequently than the current guidelines. Developers, W3C Working Groups, users,
and others are encouraged to contribute techniques.

The software and documentation components that together, conform to the requirements of this
document. This is the most common use of the term in this document and is the
usage in the guidelines.

Any software that retrieves and renders Web content for users. This may
include Web browsers, browser extensions, media players, plug-ins,
and other programs — including assistive technologies —
that help in retrieving and rendering Web content.

Components of Web Accessibility

Web accessibility depends not only on accessible user agents, but also on the availability of accessible content, a factor that is greatly influenced by the accessibility of authoring tools. For an overview of how these components of Web development and interaction work together, see:

Other Issues

One of the goals of this document is to ensure that the requirements are compatible with other software design practices. However, this document does not purport to be a complete guide to good software design. For instance, the general topic of user interface design for computer software exceeds the scope of this document, though some user interface requirements have been included because of their importance to accessibility.

This document promotes conformance to other specifications as part of
accessible design (see Principle 1). Conformance to specifications makes it easier to design
assistive technologies, and helps ensure the implementation of built-in
accessibility functions.

This document also includes some requirements to implement an accessibility
feature that may only be optional in another specification. In rare cases, a requirement in UAAG 2.0 may conflict with a requirement in
another specification. UAAG 2.0 does not define a process for resolving such
conflicts. The authors of this document anticipate that developers will
consider accessibility implications in determining how to resolve them.

Installation is an important aspect of both accessibility and general
software usability. On platforms where a user can install a user agent, the
installation (and update and removal) procedures need to be accessible. Furthermore, the
installation procedure should provide and install all components necessary to
satisfy the requirements of this document, since the risk of installation
failure increases with the number of components (e.g., plug-ins) to be installed.

This document does not include a success criteria requiring that installation
procedures be accessible. Since this document considers installation to be part
of software usage, the different aspects of installation (e.g., user interface,
documentation, and operating environment
conventions) are already covered by the complete set of success criteria.

Some of the requirements of this document may have security implications,
such as communication through APIs, and allowing programmatic read and write
access to content and user interface control. This
document assumes that features required by this document will be built on top
of an underlying security architecture. Consequently, unless permitted
explicitly in a success criteria, this document grants no conformance
exemptions based on security issues.

Developers should design user agents that enable communication with trusted
assistive technologies. Sensitive information that the user agent can access
through the user agent's user interface should also be available to assistive
technologies through secure means. For instance, if the user types a password
in the user agent user interface, do not communicate substitute characters
(such as asterisks) through an API, but rather the real password, properly
encrypted.

This document emphasizes the goal of ensuring that users, including users
with disabilities, have control over their environment for accessing the Web.
Key methods for achieving that goal include: optional self-pacing,
configurability, device-independence, interoperability, direct support for both
graphical and auditory output, and adherence to published conventions.

This document also acknowledges the importance of author preferences and the
proper implementation of specifications. However, this document includes
requirements to override certain author preferences when the user would not
otherwise be able to access that content.

Many of the requirements in this document give the user additional control
over behavior that would otherwise occur automatically. For instance, there is
a requirement to allow configuration to not open a viewport automatically
and one that requires user confirmation before submitting a form. This type of manual configuration option may be essential for some
users with disabilities, since automatic behavior may be disorienting or
interfere with navigation.

This document includes requirements for users with a variety of
disabilities, in part because some users may have more than one disability. In
some cases, it may appear that two requirements contradict each other. For
instance, a user with a physical disability may prefer that the user agent
offer more automatic behavior (to reduce demand for physical effort) than a
user with a cognitive disability (for whom automatic behavior may cause
confusion). Thus, many of the requirements in this document involve
configuration as one way to ensure that a functionality designed to improve
accessibility for one user does not interfere with accessibility for another.
Also, since a default user agent setting may be useful for one user but
interfere with accessibility for another, this document prefers configuration
requirements to requirements for default settings. Finally, there may be some
cases where, for some content, a feature required by this document is
ineffective or causes content to be less accessible, making it imperative that
the user be able to turn off the feature.

To avoid overwhelming users with an abundance of configuration options, this
document includes requirements that promote ease of configuration and
documentation of accessibility features.

Many requirements in this document promote different kinds of
independence:

Input and output device independence. This document includes some
requirements to promote device-independence natively, as well as requirements
for interoperability with assistive technologies that provide complementary
input and output functionalities.

Spatial independence. Some users may not navigate effectively in
two-dimensional visual space
(e.g., users who do not use a pointing device) or may be constrained to one
temporal dimension (e.g., users of audio-only output).

Temporal independence. Some users (e.g., users with a physical or cognitive
disability) may not be able to interact with content that changes over time, or
interaction with content that is time-sensitive.

In meeting the goals of users with disabilities, user agent developers will
also improve access to the Web for users in general. For example, users without
disabilities:

may have a text-only screen, a small screen, or a slow Internet connection
(e.g., via a mobile phone browser). These users are likely to benefit from the
same features that provide access to people with low vision or blindness.

may be in a situation where their eyes, ears, or hands are busy or
interfered with (e.g., driving to work or working in a noisy environment).
These users are likely to benefit from the same features that provide access to
people who cannot use a mouse or keyboard due to a visual, hearing, or physical
disability.

may not understand fluently the natural language of spoken content. These
users are likely to benefit from the same visual rendering of
text equivalents that make spoken
language accessible to people with a hearing disability.

The UAWG expects that software which satisfies the requirements of this
document will be more flexible, manageable, extensible, and beneficial to all
users. For example, a user agent architecture that allows programmatic access
to content and the user interface will encourage software
modularity and reuse, and will enable operation by scripting tools and
automated test engines in addition to assistive technologies.

UAAG 2.0 Guidelines

PRINCIPLE 1. Follow applicable specifications and conventions

Guideline 1.1 Observe operating environment conventions [Techniques]

Level A Success Criteria for Guideline 1.1

1.1.1 Follow and Cite Conventions:Operating environment conventions are followed and the convention sources are cited for all of the following:

Level AAA Success Criteria for Guideline 1.1

(No level AAA success criteria for Guideline 1.1)

Guideline 1.2 Support accessibility
features of technologies [Techniques]

Level A Success Criteria for Guideline 1.2

1.2.1 Accessibility Features: The accessibility features listed in the "technology accessibility features benchmark" @@Ed: Definition of this term will likely let claimant specify these in the conformance claim@@ are implemented for all technologies listed in the conformance profile.@@8.1 in UAAG10@@

Level AAA Success Criteria for Guideline 1.2

Level A Success Criteria for Guideline 1.3

1.3.1 Follow Specifications: Render content according to the technology specification. This includes any accessibility features of the technology (see Guideline 1.2) . @@2.1 in UAAG10@@

Level AA Success Criteria for Guideline 1.3

1.3.2 Handle Unrendered Technologies: If the user agent does not render a technology, it allows the user to choose a way to handle content in that technology (e.g., by
launching another application or by saving it to disk).@@NEW@@

Level AAA Success Criteria for Guideline 1.3

(No level AAA success criteria for Guideline 1.3)

Note: When a rendering requirement of another specification contradicts a
requirement of UAAG 2.0, the user agent may disregard the rendering requirement
of the other specification and still satisfy this guideline.

2.1.3: If the user can modify the state or value of a
piece of HTML or XML content through the user interface (e.g., by checking a
box or editing a text area), programmatic read access to the current
state or value is available with the same degree of write access programmatically as
is available through the user interface.

Level AA Success Criteria for Guideline 2.1

(No level AA success criteria for Guideline 2.1)

Level AAA Success Criteria for Guideline 2.1

Level A Success Criteria for Guideline 2.2

2.2.1: Access to the content required in guideline 2.1 is provided by conforming
to the following modules of the W3C Document Object Model
(DOM) Level 2 Core
Specification [DOM2CORE] and exporting bindings
for the interfaces they define:

(a) for HTML: the Core module

(b) for XML: the Core and XML modules

2.2.2: As part of satisfying Success Criterion 2.2.1:

(a) In Java and ECMAScript operating environments: the normative
bindings specified in the DOM Level 2 Core Specification [DOM2CORE] are exported, or

The user agent is not required to export the bindings outside of the user
agent process (though doing so may be useful to assistive technology
developers).

@@Note: This guideline stands apart from guideline 2.1 to emphasize
the distinction between what information is required and how to provide access
to that information. Furthermore, the DOM Level 2 Core Specification does not
provide access to current states and values referred to in provision three of guideline 2.1. For HTML
content, the interfaces defined in [DOM2HTML] do provide access to
current states and values.

Level A Success Criteria for Guideline 2.3

2.3.1: For content
other than HTML and XML, structured programmatic read access to
content is provided.

2.3.2: If the user can modify the state or value
of a piece of non-HTML/XML content through the
user interface
(e.g., by checking a
box or editing a text area), programmatic read access to the current
state or value is allowed with the same degree of write access programmatically as
is available through the user interface.

2.3.3: As part of satisfying Success Criterion 2.3.1, at least one
API is implemented, according
to this API cascade:

(a) The API is defined by a W3C Recommendation, or the API is
publicly documented and designed to enable interoperability with assistive
technologies.

(b) If no such API is available, or if available APIs do not enable the user
agent to satisfy the requirements,

(i) implement at least one publicly documented API to satisfy the requirements, and

Level AA Success Criteria for Guideline 2.3

(No level AA success criteria for Guideline 2.3)

Level AAA Success Criteria for Guideline 2.3

(No level AAA success criteria for Guideline 2.3)

Normative inclusions and
exclusions @@from UAAG10@@

"Structured programmatic access" means access through an API to recognized
information items of the content (such as the information items of the XML
Infoset [INFOSET]). Plain text has little
structure, so an API that provides access to it will be correspondingly less
complex than an API for XML content. For content more structured than plain
text, an API that only provides access to a stream of characters does not
satisfy the requirement of providing structured programmatic access. This
document does not otherwise define what is sufficiently structured access.

An API is considered "available" if the specification of the API is
published (e.g., as a W3C Recommendation) in time for integration into a user
agent's development cycle

Note: This guideline addresses content not covered by
guidelines 2.1 and 2.2.

Level A Success Criteria for Guideline 2.4

2.4.1: For graphical user agents, the bounding dimensions and coordinates of rendered graphical objects are made available. Coordinates
are relative to the point of origin in the graphical environment (e.g.,
with respect to the desktop), not the viewport.

2.4.2: For graphical user agents, the following information is available about each piece of rendered text:

(a) font family

(b) font size

(c) foreground and,

(d) background colors.

2.4.3: As part of satisfying provisions one and
two of this guideline, least one API is implemented according to the API cascade
described in Success Criterion 2.3.3 .

Level AA Success Criteria for Guideline 2.4

(No level AA success criteria for Guideline 2.4)

Level AAA Success Criteria for Guideline 2.4

(No level AAA success criteria for Guideline 2.4)

Note: User agents should provide programmatic access to
additional useful information about rendered content that is not available
through the APIs required by guidelines 2.2 and 2.3, including the correspondence (in both directions)
between graphical objects and their source in the document object, and information
about the role of each graphical object.

Level A Success Criteria for Guideline 2.5

2.5.2: If the user can modify the state or value of a user agent user interface
control (e.g., by checking a box or editing a text area), programmatic read access is allowed to the current state or value with the same
degree of write access programmatically as is available through the user
interface.

2.5.3: As part of satisfying 2.5.1 and 2.5.2, implement at least one API according to the API cascade
described in in Success Criterion 2.3.3.

Note: APIs used to satisfy the requirements of this
guideline may vary. For instance, they may be independent of a particular
operating environment (e.g., the W3C DOM), or the conventional APIs for a
particular operating environment, or the conventional APIs for programming
languages, plug-ins, or virtual machine
environments. User agent developers are encouraged to implement APIs that allow
assistive technologies to interoperate with multiple types of software in a
given operating environment (e.g., user agents, word processors, and
spreadsheet programs), as this reuse will benefit users and assistive
technology developers. User agents should always follow operating environment
conventions for the use of input and output APIs.

Level A Success Criteria for Guideline 2.6

2.6.2: As part of satisfying 2.6.1, implement at least one API according to the API cascade described in in Success Criterion 2.3.3.

Level AA Success Criteria for Guideline 2.6

(No level AA success criteria for Guideline 2.6)

Level AAA Success Criteria for Guideline 2.6

(No level AAA success criteria for Guideline 2.6)

Normative inclusions and exclusions @@from UAAG10@@

The user agent is not required to provide notification of changes in the rendering of content (e.g., due to an animation effect or an effect
caused by a style sheet) unless the document object is modified as part
of those changes.

Conformance
profile labels: Selection

Conformance detail: For both content and user agent

Note: For instance, provide programmatic notification when
user interaction in one frame causes automatic changes to content in
another.

Level A Success Criteria for Guideline 2.8

2.8.1: For an API implemented to satisfy
requirements of this document, the character encodings required for
that API are supported.

Level AA Success Criteria for Guideline 2.8

(No level AA success criteria for Guideline 2.8)

Level AAA Success Criteria for Guideline 2.8

(No level AAA success criteria for Guideline 2.8)

Normative inclusions and exclusions @@from UAAG10@@

Conformance detail: For both content and user agent

Note: Support for character encodings is an important part
of ensuring that text is correctly communicated to assistive technologies. For
example, the DOM Level 2 Core Specification [DOM2CORE], section 1.1.5
requires that the DOMString type be encoded using UTF-16.

Level A Success Criteria for Guideline 2.10

Level AA Success Criteria for Guideline 2.10

2.10.1: For APIs implemented to satisfy the requirements of this document, programmatic exchanges proceed in a timely manner.

Level AAA Success Criteria for Guideline 2.10

(No level AAA success criteria for Guideline 2.10)

Note: For example, the programmatic exchange of information
required by other guidelines in this document should be efficient enough to
prevent information loss, a risk when changes to content or user interface
occur more quickly than the communication of those changes. Timely exchange is
also important for the proper synchronization of alternative renderings. The
techniques for this guideline explain how developers can reduce communication
delays. This will help ensure that assistive technologies have timely access to
the document object model and other
information that is important for providing access.

(b) non-synchronized alternatives (e.g., short text alternatives, long descriptions) can be rendered as replacements for the original rendered content. If the new item has different dimensions, then a user option controls whether the dimensions of the original content are used or the dimensions of the new content, which will cause the document to reflow accordingly.@@Implied in 2.3 in UAAG10@@

3.2.3 Available Programmatically: If an item in the alternative content stack is plain text (e.g., short text alternative), then it is available programmatically, even when not rendered. @@Implied in 2.3 in UAAG10@@

Level AA Success Criteria for Guideline 3.2

3.2.4 Simultaneous Rendering: The user has the option to simultaneously render any and all items from the alternative content stack (which will cause the document to reflow accordingly) unless the user agent can recognize a mutual exclusion (e.g. conflicting soundtracks).@@NEW@@

3.2.5 Configurable Default Rendering: The user has the option to set preferences for which items in an alternative content stack will be rendered by default. @@2.9 in UAAG10@@

Level AAA Success Criteria for Guideline 3.2

(No level AAA success criteria for Guideline 3.2)

@@New Technique 3.2.5=User agents should expose configuration choices in as highly visible a fashion as is practical such as on a menu entry or dialog settings devoted to accessibility@@.

Guideline 3.3 Provide control of content that may reduce accessibility [Techniques]

Note: The guideline only applies to images, animations, video, audio, etc. that the user agent can recognize.

Level A Success Criteria for Guideline 3.3

3.3.1 Background Image Toggle: The user has the option to hide/show background images@@DEFINE@@ (i.e., images that are rendered on the base background). @@3.1 in UAAG10@@

3.3.7 Retrieval Progress: Show the progress of content retrieval. @@NEW@@

3.3.8 Slow Multimedia: The user can slow the presentation rate
of recognized prerecorded audio and animation content, such that all of the following are true:@@4.4 in UAAG10@@

if only an audio track is present, provide at least one setting between 75% and 80% of the
original speed.

if a visual track is present, provide at
least one setting between 40% and 60% of the original speed.

when audio and video tracks are synchronized: above 75% of the original speed, maintain synchronization; below 75% the user agent is not required to render the audio track.

3.3.9 Stop/Pause/Resume Multimedia: The user can stop, pause, and resume
rendered audio and animation content (including
video and animated images) that last three or more seconds at their default
playback rate.@@4.5 in UAAG10@@

3.3.10 Navigate Multimedia: The user can navigate efficiently
within rendered audio and animations (including video and animated
images) that last three or more seconds at their default playback
rate.@@4.5 in UAAG10@@

Level AA Success Criteria for Guideline 3.3

(No level AA success criteria for Guideline 3.3)

Level AAA Success Criteria for Guideline 3.3

(No level AAA success criteria for Guideline 3.3)

@@Tech=Provide the user with the ability to toggle whether the base user agent executes content that it is able to . - if cond. content exists reveal it (2.3) @@Tech=Provide the user with the ability to toggle the loading of plugins that execute content the base browser is unable to execute - if cond. content exists reveal it (2.3)

Level A Success Criteria for Guideline 3.4

3.4.1 Relationships Available Programmatically: Make explicitly-defined relationships in the content (e.g., labeled_by, table_header_for, etc.) available programmatically. @@Expanded 10.1 in UAAG10@@

3.4.2 Access Relationships: The user can access information from explicitly-defined relationships in the content (e.g., what is form control's label?, what is label's form control?, what is cell's table header?, etc.). @@Expanded 10.1 in UAAG10@@

Level AA Success Criteria for Guideline 3.4

3.4.3 Location in Hierarchy: For content in a hierarchy (e.g., tree node, nested frame), the user can view the path of nodes leading from the root to the content.@@NEW@@

Level AA Success Criteria for Guideline 3.5

(No level AA success criteria for Guideline 3.5)

Level AAA Success Criteria for Guideline 3.5

3.5.2 Repair Empty Alternatives: The user has the option of receiving generated repair text when the user agent recognizes that the author has provided empty alternative
content for an enabled element. @@2.8 in UAAG10@@

(b) if no such utility is available, the range supported by the
conventional APIs of the
operating environment for drawing text.

Level AA Success Criteria for Guideline 3.7

(No level AA success criteria for Guideline 3.7)

Level AAA Success Criteria for Guideline 3.7

3.7.4 Maintain contrast: The user has the option to constrain the configuration of the default text foreground color, background
color and highlighting colors, so that text contrast is maintained between them. @@NEW@@

3.9.2 Option Range: The user can set all of the speech characteristics offered by the speech synthesizer, according to the full range of values available, overriding any values specified by
the author:
@@4.11 in UAAG10@@

Level AA Success Criteria for Guideline 3.9

3.9.3 Speech Characteristics: The user can set all of the following synthesized speech characteristics,
overriding any values specified by
the author:
@@4.12 in UAAG10@@

(a) pitch ("pitch" refers to the average frequency of the speaking voice),

(b) pitch range ("pitch range" specifies a variation in average frequency), and

(c) speech stress.
("speech stress" refers to the height of "local peaks" in the intonation contour of the
voice).@@richness deleted since not in CSS3 http://www.w3.org/TR/2004/WD-css3-speech-20041216/@@

3.9.4 Speech Features: The following speech features are provided:
@@4.13 in UAAG10@@

(a) user-defined extensions to the synthesized speech dictionary,

(b) "spell-out", where text is spelled
one character at a time, or according to language-dependent pronunciation
rules,

(c) at least two ways of speaking numerals: one
where numerals are spoken as individual digits, and one where full numbers are
spoken, and

(d) at least two ways of speaking punctuation: one where punctuation is spoken literally, and one where punctuation is
rendered as natural pauses.

Level AA Success Criteria for Guideline 3.10

Level AAA Success Criteria for Guideline 3.10

(No level AAA success criteria for Guideline 3.10)

Guideline 3.11 Help user to use and orient within viewports [Techniques]

Level A Success Criteria for Guideline 3.11

3.11.1 Highlight Viewport: The viewport with the current focus is highlighted (including any frame that
takes current focus) using a highlight
mechanism that does not rely on rendered text foreground and background
colors alone (e.g., a thick outline).@@10.6 in UAAG10@@

3.11.2 Move Viewport to Selection: When a viewport's selection changes, the viewport moves as necessary to ensure that the new selection is at least
partially in the viewport.@@5.4 in UAAG10@@

3.11.3 Move Viewport to Focus: When a viewport's content focus changes, the viewport moves as necessary to ensure that the new content focus is at least
partially in the viewport.@@5.4 in UAAG10@@

3.11.5 Scrollbars: Graphical viewports include scrollbars if the rendered content (including after user preferences have been applied) extends beyond the viewport dimensions, overriding any values specified by
the author.@@NEW@@

3.11.6 Viewport History: If the user agent maintains a viewport history mechanism (e.g., via the "back button") that stores previous "viable" states (i.e., that have not been negated by the content, user agent settings or user agent extensions), it maintains
information about the point of regard and it restores the saved values when the user returns to a state in the history.@@9.4 in UAAG10@@

Level AA Success Criteria for Guideline 3.11

3.11.7 Open on Request: The user has the option of having "top-level" viewports (e.g., windows) only open
on explicit user request. In this mode, instead of opening a viewport automatically, alert the user and
allow the user to open it with an explicit request (e.g., by
confirming a prompt or following a link generated by the user agent).@@5.3 in UAAG10@@

3.11.9 Stay on Top: The user has the option of having the viewport with the current focus remain "on top" of all
other viewports with which it overlaps.@@5.2 in UAAG10@@

3.11.10 Close Viewport: The user can close any "top-level" viewport.@@5.3 in UAAG10@@

3.11.11 Same UI: The user has the option of having all "top-level" viewports follow the same user interface configuration as the current or spawning viewport, including the same "chrome".@@NEW@@

Level AAA Success Criteria for Guideline 3.11

3.11.12 Indicate Viewport Position: Indicate the viewport's position relative to rendered content (e.g., the proportion along an audio or video timeline, the
proportion of a Web page before the current position ).@@10.7 in UAAG10@@

3.12.4 Extensions Focusable: The user interface focus can navigate within extensions to the user interface "chrome". @@If it knows how to insert and render the extension in its chrome, then it should have good enough programmatic access and knowledge to properly give focus. - Tech XUL spec for FF@@

Level A Success Criteria for Guideline 3.13

Level AA Success Criteria for Guideline 3.13

3.13.2 Outline View: An "outline"
view of rendered content is provided,
composed of labels for important structural elements (e.g., heading text, table
titles, form titles, and other labels that are part of the content). Note: What constitutes a label is defined by each markup language specification.
For example, in HTML, a heading (H1-H6) is a label
for the section that follows it, a CAPTION is a label for a table,
and the title attribute is a label for its element.@@10.4 in UAAG10@@

Level AAA Success Criteria for Guideline 3.13

3.13.3 Configure Set of Important Elements: The user has the option to configure the set of important
elements for the "outline" view, including by element type (e.g., headers). @@9.10 in UAAG10@@

PRINCIPLE 4. Ensure that the user interface is operable

@@The UAWG is currently working to ensure that sufficient requirements are in place regarding how keyboard shortcuts are conveyed to the user (e.g. visual indicators, documentation, etc.). Input from area experts would be welcome.@@

@@The UAWG is also currently working to ensure that the requirements properly cover interaction with video and dynamic Web content. Input from area experts would be welcome.@@

Level A Success Criteria for Guideline 4.1

4.1.1 Keyboard: The user can, through keyboard input alone, navigate to and operate all of the functions included in the user interface (e.g., navigating and selecting content within views, operating the user interface "chrome", installing
and configuring the user agent, and accessing documentation), except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints (e.g. freeform drawing). This applies to at least one mechanism per "browsing outcome"@@DEFINE@@, allowing
non-keyboard accessible mechanisms to remain available (e.g.,
providing resizing with mouse-"handles" and with keystrokes).@@1.1 in UAAG10@@[ATAG 2.0]

4.1.3 No Keyboard Trap: If focus can be moved to a component with the keyboard, then at least one of the following is true:
@@WCAG2 concept@@

(a) standard keys: focus can be moved away from the component with the keyboard using standard navigation keys (i.e., unmodified arrow or tab keys), or

(b) documented non-standard keys: focus can be moved away from the component with non-standard keys and the user is advised of the method.

4.1.4 Separate Activation: The user has the option to have selection separate from activation
(e.g., navigating through the items in a dropdown menu without
activating any of the items).@@9.5 in UAAG10@@[ATAG 2.0]

4.1.5 Available Keystrokes: The user can always determine available binding information in a centralized fashion (e.g., a list of bindings) or a distributed fashion (e.g., by keyboard shortcuts listed in user interface menus) for the following:
@@11.1,11.2 in UAAG10@@

4.1.7 "Chrome" Navigation: The user can use the keyboard to traverse all of the controls forwards and backwards, including controls in floating toolbars, panels, user agent extensions @@DEFINE@@, etc. using conventions of the platform (e.g., via "tab", "shift-tab", "ctrl-tab", "ctrl-shift-tab").[ATAG 2.0]

Level AA Success Criteria for Guideline 4.1

4.1.8 Accelerator Keys: If any of the following functionalities are implemented by the
user agent, the user has the option to enable
key-plus-modifier-key (or single-key) access to them:@@11.5 in UAAG10@@[ATAG 2.0]

4.1.10 User Override any Binding: The user can override any binding that is part of the user agent default input configuration except for conventional bindings for the operating environment (e.g., for access to help). The keyboard combinations offered for rebinding include single key and key plus modifier keys if these are available in the operating environment. @@11.3,11.4 in UAAG10@@

Level AAA Success Criteria for Guideline 4.1

4.1.11 Intergroup Navigation: If logical groups of focusable controls (e.g., toolbars, dialogs, labeled groups, panels) are present, the user can use the keyboard to navigate to a focusable control in the next and previous groups.[ATAG 2.0]@@NEW@@

4.1.12 Group Navigation: If logical groups of focusable controls are present, the user can use the keyboard to navigate to the first, last, next and previous focusable controls in the current group.[ATAG 2.0]@@NEW@@

Level A Success Criteria for Guideline 4.2

4.2.1 All Available: The user can activate, through keyboard input alone, all
input device event handlers (including those for pointing devices, voice, etc.) that are
explicitly associated with the element designated by the content focus.@@1.2 in UAAG10@@

4.2.2 Show All: For the element with content focus, the list
of input device event types for which there are
event handlers explicitly associated
with the element are provided. @@9.6 in UAAG10@@

4.2.3 Activate All: The user can activate, as a group, all event
handlers of the same input device event type, for the same control. @@1.2 in UAAG10@@

Level A Success Criteria for Guideline 4.6

(No level A success criteria for Guideline 4.6)

Level AA Success Criteria for Guideline 4.6

4.6.1 Search Rendered: The user can perform a search within rendered (e.g., not hidden with a style) content for text and text alternatives for a sequence
of characters from the document character set.@@9.8 in UAAG10@@

4.6.2 Bi-Directional: The user has the option of searching forward or backward (in document order) from any selected
or focused location in content.@@NEW@@

4.6.3 Match Found: When there is a match, both of the following are true:

(a) move: the viewport moves so that the matched text content is at least partially
within it, and@@9.8 in UAAG10@@

(b) search again: the user can search for the next instance of the text from the
location of the match.@@9.8 in UAAG10@@

4.6.4 No Match: The user is alerted when there is no match or after the last match in content (i.e.,
prior to starting the search over from the beginning of content).@@9.8 in UAAG10@@

4.6.5 Case Insensitive: There is a case-insensitive search option.@@9.8 in UAAG10@@

Principle 5: Ensure that user interface is understandable

Guideline 5.1 Help users avoid unnecessary messages [Techniques]

Level A Success Criteria for Guideline 5.1

(No level A success criteria for Guideline 5.1)

Level AA Success Criteria for Guideline 5.1

5.1.1 Option to Ignore: The user has the option to turn off rendering of non-essential or low priority text messages, based on priority properties defined by the author (e.g., ignoring messages marked "polite" using ARIA ). @@NEW@@

Level AAA Success Criteria for Guideline 5.1

Level A Success Criteria for Guideline 5.2

(No level A success criteria for Guideline 5.2)

Level AA Success Criteria for Guideline 5.2

5.2.1 Form Submission: The user has the option to confirm (or cancel) any
form submission made while content focus is not on the submitting control (e.g., forms that submit when Enter is pressed). @@5.5 in UAAG10@@

Level AAA Success Criteria for Guideline 5.2

(No level AAA success criteria for Guideline 5.2)

Guideline 5.3 Document the user agent user interface
including all accessibility features [Techniques]

Level A Success Criteria for Guideline 5.3

5.3.1 Accessible Format: At least one
version of the documentation is either:
@@12.1 in UAAG10@@

(a) "A" accessible: Web content and conforms to WCAG 2.0 Level "A" (although it is not necessary
for the documentation to be delivered on-line), or,

(b) accessible platform format: not Web content and conforms to a published accessibility
benchmark that is identified in the conformance
claim (e.g.,
when platform-specific documentation systems are used).

5.3.2 Document Accessibility Features: All user agent
features that benefit accessibility @@DEFINE - as specified in the conformance claim@@ are documented.@@12.2 in UAAG10@@

Level AA Success Criteria for Guideline 5.3

5.3.3 Changes Between Versions: Changes to features that benefit
accessibility since the
previous version of the user agent are documented. @@12.4 in UAAG10@@

5.3.4 Centralized View: There is a centralized view of all
features of the user agent that benefit accessibility, in a dedicated section
of the documentation.@@12.5 in UAAG10@@

Level AAA Success Criteria for Guideline 5.3

5.3.5 Context Sensitive Help: There is context-sensitive help on all user agent features that benefit accessibility.@@NEW@@

In the context of rendered content this means to execute or carry out one or more behaviors associated with an
enabled element.
In the context of the user interface "chrome", this means to execute or carry out one or more behaviors associated with a component of the
user agent user interface.
The effect of activation depends on the type of the
user interface control.
For instance, when a link is activated, the user agent generally retrieves the linked
Web resource.
When a form element is activated, it may change state (e.g., check boxes) or may take user input (e.g., a text entry field).

To make the user aware
of some event, without requiring acknowledgement. For example, the user agent
may alert the user that new content is available on the server by displaying a
text message in the user agent's status bar.

Note: Specifications vary in how completely they define how and when to render alternative content.

alternative content stack:

The set of alternative content items for a given position in content. The items may be mutually exclusive (e.g., regular contrast graphic vs. high contrast graphic) or non-exclusive (e.g., caption track that can play at the same time as a sound track).

graphically displaying a sequence of snapshots within the same region
(e.g., as is done for video and animated images). The series of snapshots may
be provided by a single resource (e.g., an animated GIF image) or from distinct
resources (e.g., a series of images downloaded continuously by the user
agent).

scrolling text (e.g., achieved through markup or style sheets).

displacing graphical objects around the viewport (e.g., a picture of a ball
that is moved around the viewport giving the impression that it is bouncing off
of the viewport edges). For instance, the SMIL 2.0
[SMIL20] animation modules explain
how to create such animation effects in a declarative manner (i.e., not by
composition of successive snapshots).

An application programming interface
(API) defines how
communication may take place between applications.

Implementing APIs that are independent of a particular operating environment
(as are the W3C DOM Level 2 specifications) may reduce implementation costs for
multi-platform user agents and promote the development of multi-platform
assistive technologies. Implementing conventional APIs for a particular
operating environment may reduce implementation costs for assistive technology
developers who wish to interoperate with more than one piece of software
running on that operating environment.

A "device API" defines how communication may take place
with an input or output device such as a keyboard, mouse, or video card.

In this document, an "input/output API" defines how
applications or devices communicate with a user agent. As used in this
document, input and output APIs include, but are not limited to, device APIs.
Input and output APIs also include more abstract communication interfaces than
those specified by device APIs. A "conventional input/output API" is one that
is expected to be implemented by software running on a particular operating
environment. For example, the conventional input APIs of the
user agent are for the mouse and
keyboard. For touch screen devices or mobile devices, conventional input
APIs may include stylus, buttons, and voice. The graphical
display and sound card are considered conventional output devices for a
graphical desktop computer environment, and each has an associated
API.

In the context of this document, an assistive technology
is a user agent that:

relies on services (such as retrieving Web
resources and parsing markup) provided by one or more other "host" user
agents. Assistive technologies communicate data and messages with host user
agents by using and monitoring APIs.

provides services beyond those offered by the host user agents to meet the
requirements of users with disabilities. Additional services include
alternative renderings (e.g., as synthesized speech or magnified content),
alternative input methods (e.g., voice), additional navigation or orientation
mechanisms, and content transformations (e.g., to make tables more
accessible).

Examples of assistive technologies that are important in the context of this
document include the following:

screen magnifiers, which are used by people with visual disabilities to
enlarge and change colors on the screen to improve the visual readability of
rendered text and images.

screen readers, which are used by people who are blind or have reading
disabilities to read textual information through synthesized speech or braille
displays.

voice recognition software, which may be used by people who have some
physical disabilities.

alternative keyboards, which are used by people with certain physical
disabilities to simulate the keyboard.

alternative pointing devices, which are used by people with certain
physical disabilities to simulate mouse pointing and button
activations.

Beyond this document, assistive technologies consist of
software or hardware that has been specifically designed to assist people with
disabilities in carrying out daily activities. These technologies include
wheelchairs, reading machines, devices for grasping, text telephones, and
vibrating pagers. For example, the following very general definition of
"assistive technology device" comes from the (U.S.) Assistive Technology Act of
1998 [AT1998]:

Any item, piece of equipment, or product system, whether acquired
commercially, modified, or customized, that is used to increase, maintain, or
improve functional capabilities of individuals with
disabilities.

Content rendered as sound through an
audio viewport. The audio track may be all or part of the audio portion presentation (e.g., each instrument may have a track, or each stereo channel may have a track).

audio description - also called described video, video description and descriptive narration

An equivalent alternative that takes the form of narration added to the audio to describe important visual details that cannot be understood from the main soundtrack alone. Audio description of video provides information about actions, characters, scene changes, on-screen text, and other visual content. In standard audio description, narration is added during existing pauses in dialogue. In extended audio description, the video is paused so that there is time to add additional description.

authors

The people who have worked either alone or collaboratively to create the content (includes content authors, designers, programmers, publishers, testers, etc.).

An equivalent alternative that takes the form of text presented and synchronized with synchronized media to provide not only the speech, but also non-speech information conveyed through sound, including meaningful sound effects and identification of speakers. In some countries, the term "subtitle" is used to refer to dialogue only and "captions" is used as the term for dialogue plus sounds and speaker identification. In other countries, "subtitle" (or its translation) is used to refer to both. Open captions are captions that are always
rendered with a visual track; they cannot be turned off. Closed
captions are captions that may be turned on and off. The
captions requirements of this document assume that the user agent can recognize the captions as such.Note: Other terms that include the word "caption" may have
different meanings in this document. For instance, a "table caption" is a title
for the table, often positioned graphically above or below the table. In this
document, the intended meaning of "caption" will be clear from
context.

A mapping from a character set
definition to the actual code units used to represent the data. Refer to the
Unicode specification [UNICODE] for more information
about character encodings. Refer to "Character Model for the World Wide Web"
[CHARMOD] for additional
information about characters and character encodings.

A collated text transcript is a text
equivalent of a movie or other animation. More specifically, it is the
combination of the text transcript of the
audio track and the text equivalent of
the visual track. For example, a collated
text transcript typically includes segments of spoken dialogue interspersed
with text descriptions of the key visual elements of a presentation (actions,
body language, graphics, and scene changes). See also the definitions of
text transcript and
audio description. Collated text
transcripts are essential for individuals who are deaf-blind.

In the context of this document, the verbs "to control"
and "to configure" share in common the idea of governance such as a user may
exercise over interface layout, user agent behavior, rendering style, and other
parameters required by this document. Generally, the difference in the terms
centers on the idea of persistence. When a user makes a change by
"controlling" a setting, that change usually does not persist beyond that user
session. On the other hand, when a user "configures" a setting, that setting
typically persists into later user sessions. Furthermore, the term "control"
typically means that the change can be made easily (such as through a keyboard
shortcut) and that the results of the change occur immediately. The term
"configure" typically means that making the change requires more time and
effort (such as making the change via a series of menus leading to a dialog
box, or via style sheets or scripts). The results of "configuration" might not
take effect immediately (e.g., due to time spent reinitializing the system,
initiating a new session, or rebooting the system).

In order to be able to configure and control the user agent, the user needs
to be able to "write" as well as "read" values for these parameters.
Configuration settings may be stored in a profile.
The range and granularity of the changes that can be controlled or configured
by the user may depend on limitations of the operating environment or
hardware.

Both configuration and control can apply at different "levels": across
Web resources (i.e., at the user agent
level, or inherited from the operating environment), to the
entirety of a Web resource, or to components of a Web resource (e.g., on a
per-element basis).

A global configuration is one
that applies across elements of the same Web resource, as well as across Web
resources.

User agents may allow users to choose configurations based on various
parameters, such as hardware capabilities or natural language preferences.@@POINT TO NEW GUIDELINE ON HOW TO SAVE SETTTINGS@@

It is used to mean the content of an HTML or XML element, in the sense
employed by the XML 1.0 specification ([XML], section 3.1): "The text between
the start-tag and end-tag is called the element's content." Context should
indicate that the term content is being used in this sense.

empty
content (which may be alternative content) is either a
null value or an empty string (i.e., one that is zero characters long). For
instance, in HTML, alt="" sets the value of the alt
attribute to the empty string. In some markup languages, an element may have
empty content (e.g., the HR element in HTML).

In general usage, the term "document object" refers to the
user agent's representation of data (e.g., a document). This data generally
comes from the document source, but
may also be generated (e.g., from style sheets, scripts, or transformations),
produced as a result of preferences set within the user agent, or added as the
result of a repair performed automatically by the user agent. Some data that is
part of the document object is routinely rendered (e.g., in HTML, what
appears between the start and end tags of elements and the values of attributes
such as alt, title, and summary). Other
parts of the document object are generally processed by the user agent without
user awareness, such as
DTD- or schema-defined
names of element types and attributes, and other attribute values such as
href and id. Most of the requirements of this
document apply to the document object after its construction. However, a few
guidelines (e.g., @@) may affect the construction of the document
object.

A "document object model" is the abstraction that governs
the construction of the user agent's document object. The document object model
employed by different user agents may vary in implementation and sometimes in
scope. This specification requires that user agents implement the
APIs defined
in Document Object Model (DOM) Level 2 specifications
([DOM2CORE] and
[DOM2STYLE]) for access to
HTML, XML, and CSS
content. These DOM APIs allow authors to access and modify the content via a
scripting language (e.g., JavaScript) in a consistent manner across different
scripting languages.

In this document, a document character set (a concept from
SGML) is a collection of abstract characters that a format specification allows
to appear in an instance of the format. A document character set consists of:

A "repertoire": A set of abstract characters, such as the Latin letter "A,"
the Cyrillic letter "I," and the Chinese character meaning "water."

Code positions: A set of integer references to characters in the
repertoire.

For instance, the character set required by the HTML 4 specification
[HTML4] is defined in the Unicode
specification [UNICODE]. Refer to "Character
Model for the World Wide Web" [CHARMOD] for more information
about document character sets.

In this document, the term "document source" refers to the
data that the user agent receives as the direct result of a request for a
Web resource (e.g., as the result of an
HTTP/1.1 [RFC2616] "GET", or as the result
of viewing a resource on the local file system). The document source generally
refers to the "payload" of the user agent's request, and does not generally
include information exchanged as part of the transfer protocol. The document
source is data that is prior to any repair by the user agent (e.g., prior to
repairing invalid markup). "Text source" refers to the text portion of
the document source.

Documentation refers to information that supports the use
of a user agent. This information may be found, for example, in manuals,
installation instructions, the help system, and tutorials. Documentation may be
distributed (e.g., some parts may be delivered on CD-ROM, others on the Web).
See guideline 5.3 for information about documentation requirements.

This document uses the terms "element" and "element type"
primarily in the sense employed by the XML 1.0 specification
([XML], section 3): an element type is
a syntactic construct of a document type definition (DTD) for its application.
This sense is also relevant to structures defined by XML schemas. The document
also uses the term "element" more generally to mean a type of content (such as
video or sound) or a logical construct (such as a header or list).

An enabled element is a piece of content
with associated behaviors that can be activated through the user interface or
through an API. The set
of elements that a user agent enables is generally derived from, but is not
limited to, the set of interactive
elements defined by implemented markup languages.

Some elements may only be enabled elements for part of a user session. For
instance, an element may be disabled by a script as the result of user
interaction. Or, an element may only be enabled during a given time period
(e.g., during part of a SMIL 1.0 [SMIL] presentation). Or, the user
may be viewing content in "read-only" mode, which may disable some
elements.

A disabled element is a piece of content that is potentially an
enabled element, but is not in the current session. One example of a disabled
element is a menu item that is unavailable in the current session; it might be "grayed out" to show that it is disabled. Generally, disabled elements will be
interactive elements that are not
enabled in the current session. This document distinguishes disabled elements
(not currently enabled) from non-interactive elements
(never enabled).

For the requirements of this document, user
selection does not constitute user interaction with enabled elements. See
the definition of content focus.

Note: The term "active element" is not used in this
document since it may suggest several different concepts, including:
interactive element, enabled element, an element "in the process of being
activated" (which is the meaning of :active in CSS2
[CSS2], for example).

The term "equivalent" is used in this document as it is
used in the Web Content Accessibility Guidelines 1.0
[WCAG10]:

Content is "equivalent" to other content when both fulfill essentially the
same function or purpose upon presentation to the user. In the context of this
document, the equivalent must fulfill essentially the same function for the
person with a disability (at least insofar as is feasible, given the nature of
the disability and the state of technology), as the primary content does for
the person without any disability.

Equivalents include text equivalents
(e.g., text equivalents for images, text transcripts for audio tracks, or
collated text transcripts for a movie) and non-text equivalents (e.g., a
prerecorded audio description of a visual track of a movie, or a sign
language video rendition of a written text).

Each markup language defines its own mechanisms for specifying
alternative content, and these
mechanisms may be used by authors to provide text equivalents. For instance, in
HTML 4 [HTML4] or SMIL 1.0
[SMIL], authors may use the
alt attribute to specify a text equivalent for some elements. In
HTML 4, authors may provide equivalents and other alternative content in
attribute values (e.g., the summary attribute for the
TABLE element), in element content (e.g., OBJECT for
external content it specifies, NOFRAMES for frame equivalents, and
NOSCRIPT for script equivalents), and in prose. Please consult the
Web Content Accessibility Guidelines 1.0
[WCAG10] and its associated
Techniques document [WCAG10-TECHS] for more
information about equivalents.

User agents often perform a task when an event having a
particular "event type" occurs, including user interface events, changes to
content, loading of content, and requests from the operating environment. Some
markup languages allow authors to specify that a script, called an
event
handler, be executed when an event of a given type occurs. An
event handler is explicitly associated with an
element when the event handler is associated with that element
through markup or the DOM. The term "event bubbling" describes a
programming style where a single event handler dispatches events to more than
one element. In this case, the event handlers are not explicitly associated
with the elements receiving the events (except for the single element that
dispatches the events).

Note: The combination of HTML, style sheets, the Document
Object Model (DOM), and scripting is commonly referred to as "Dynamic HTML" or DHTML. However, as there is no W3C specification that
formally defines DHTML, this document only refers to event handlers and
scripts.

Some examples of explicit user requests include when the
user selects "New viewport," responds "yes" to a prompt in the user agent's
user interface, configures the user agent to behave in a certain way, or
changes the selection or focus with the keyboard or pointing device.

Note: Users make mistakes. For example, a
user may inadvertently respond "yes" to a prompt instead of "no." In this
document, this type of mistake is still considered an explicit user
request.

In this document, the term "content focus" refers to a user agent mechanism that has all of the following
properties:

It designates zero or one element in content
that is either enabled or
disabled. In general, the focus
should only designate enabled elements, but it may also designate disabled
elements.

It has state, i.e., it may be "set" on an enabled element, programmatically
or through the user interface. Some content specifications (e.g., HTML, CSS)
allow authors to associate behavior with focus set and unset
events.

Once it has been set, it may be used to trigger other behaviors associated
with the enabled element (e.g., the user may activate a link or change the
state of a form control). These behaviors may be triggered programmatically or
through the user interface (e.g., through keyboard events).

User interface mechanisms may resemble content focus, but do not satisfy all
of the properties. For example, designers of word processing software often
implement a "caret" that indicates the current location of text input or
editing. The caret may have state and may respond to input device events, but
it does not enable users to activate the behaviors associated with enabled
elements.

The user interface focus shares the properties of the content focus except
that, rather than designating pieces of content, it designates zero or one
control of the
user agent user interface
that has associated behaviors (e.g., a radio button, text box, or menu).

On the screen, the user agent may highlight the content focus in a variety of
ways, including through colors, fonts, graphics, and magnification. The user
agent may also highlight the content focus when rendered as synthesized speech,
for example through changes in speech prosody. The
dimensions of the rendered content focus may
exceed those of the viewport.

In this document, each viewport is expected to have at most one content
focus and at most one user interface focus. This document includes requirements
for content focus only, for user interface focus only, and for both. When a
requirement refers to both, the term "focus" is used.

When several viewports coexist, at most one viewport's
content focus or user interface focus responds to input
events; this is called the current focus.

This document uses the term "image" to refer (as is
commonly the case) to pictorial content. However, in this
document, term image is limited to static (i.e., unmoving) visual information.
See also the definition of animation.

This specification intentionally does not identify which "important elements" must be navigable as this will vary by specification. What constitutes "efficient navigation" may depend on a number of factors as well, including the "shape" of content (e.g., sequential navigation of long lists is not efficient) and desired granularity (e.g., among tables, then among the cells of a given table). Refer to the Techniques document [UAAG10-TECHS] for information about identifying and navigating important elements.

An input configuration is the set of "bindings" between
user agent functionalities and user interface input mechanisms (e.g.,
menus, buttons, keyboard keys, and voice commands). The default input
configuration is the set of bindings the user finds after installation of the
software.
Input configurations may be affected by author-specified bindings (e.g.,
through the accesskey attribute of HTML 4
[HTML4]).

An interactive element is piece of content that, by specification or by programmatic enablement, may have associated behaviors to be executed or carried out as a result of user or programmatic interaction." @@edit the rest@@For instance, the interactive
elements of HTML 4
[HTML4] include: links, image maps,
form elements, elements with a value for the longdesc attribute,
and elements with event handlers
explicitly associated with them (e.g., through the various "on" attributes).
The role of an element as an interactive element is subject to applicability. A non-interactive
element is an element that, by format specification, does not have associated
behaviors. The expectation of this document is that interactive elements become
enabled elements in some sessions,
and non-interactive elements never become enabled elements.

What is identified as "normative" is required for
conformance (noting that one may
conform in a variety of well-defined ways to this document). What is identified
as "informative" (sometimes, "non-normative") is never required for
conformance.

In this document, the term "override" means that one
configuration or behavior preference prevails over another. Generally, the
requirements of this document involve user preferences prevailing over author
preferences and user agent default settings and behaviors. Preferences may be
multi-valued in general (e.g., the user prefers blue over red or yellow), and
include the special case of two values (e.g., turn on or off blinking text
content).

A placeholder is content generated by the user agent to
replace author-supplied content. A placeholder may be generated as the result
of a user preference (e.g., to not render images) or as repair content (e.g., when an image
cannot be found). Placeholders can be any type of content, including text,
images, and audio cues. Placeholders should identify the technology of the object of which it is holding the place. Placeholders will appear in the alternative content stack.

The point of regard is a position in
rendered content that the user is
presumed to be viewing. The dimensions of the point of regard may vary. For
example, it may be a point (e.g., a moment during an audio rendering or a
cursor position in a graphical rendering), or a range of text (e.g., focused
text), or a two-dimensional area (e.g., content rendered through a
two-dimensional graphical viewport). The point of regard is almost always
within the viewport, but it may exceed the spatial or temporal
dimensions of the viewport (see the
definition of rendered content for
more information about viewport dimensions). The point of regard may also refer
to a particular moment in time for content that changes over time (e.g., an
audio-only presentation).
User agents may determine the point of regard in a number of ways, including
based on viewport position in content, content focus, and
selection. The stability of the point of
regard is addressed by @@.

A profile is a named and persistent representation of user
preferences that may be used to configure a user agent. Preferences include
input configurations, style preferences, and natural language preferences. In
operating environments with
distinct user accounts, profiles enable users to reconfigure software quickly
when they log on. Users may share their profiles with one another.
Platform-independent profiles are useful for those who use the same user agent
on different platforms.

A user agent renders a document by applying formatting
algorithms and style information to the document's elements. Formatting depends
on a number of factors, including where the document is rendered: on screen, on
paper, through loudspeakers, on a braille display, or on a mobile device. Style
information (e.g., fonts, colors, and synthesized speech prosody) may come from
the elements themselves (e.g., certain font and phrase elements in HTML), from
style sheets, or from user agent settings. For the purposes of these
guidelines, each formatting or style option is governed by a property and each
property may take one value from a set of legal values. Generally in this
document, the term
"property"
has the meaning defined in CSS 2 ([CSS2], section 3). A reference to "styles" in this document means a set of style-related properties. The value
given to a property by a user agent at installation is called the property's
default value.

Authors encode information in many ways, including in
markup languages, style sheet languages, scripting languages, and protocols.
When the information is encoded in a manner that allows the user agent to
process it with certainty, the user agent can "recognize" the information. For
instance, HTML allows authors to specify a heading with the H1
element, so a user agent that implements HTML can recognize that content as a
heading. If the author creates a heading using a visual effect alone (e.g.,
just by increasing the font size), then the author has encoded the heading in a
manner that does not allow the user agent to recognize it as a heading.

Some requirements of this document depend on content roles, content
relationships, timing relationships, and other information supplied by the
author. These requirements only apply
when the author has encoded that information in a manner that the user agent
can recognize. See the section on
conformance for more information
about applicability.

In practice, user agents will rely heavily on information that the author
has encoded in a markup language or style sheet language. On the other hand,
behaviors, style, meaning encoded in a script, and
markup in an unfamiliar XML namespace may not be recognized by the user agent
as easily or at all. The Techniques document
[UAAG10-TECHS] lists some
markup known to affect accessibility that user agents can recognize.

Rendered content is the part of content
that the user agent makes available to the user's senses of sight and hearing
(and only those senses for the purposes of this document). Any content that
causes an effect that may be perceived through these senses constitutes
rendered content. This includes text characters, images, style sheets, scripts,
and anything else in content that, once processed, may be perceived through
sight and hearing.

The term "rendered text" refers to text content
that is rendered in a way that communicates information about the characters
themselves, whether visually or as synthesized speech.

In the context of this document,
invisible
content is content that is not rendered but that may influence
the graphical rendering (e.g., layout) of other content. Similarly,
silent
content is content that is not rendered but that may influence
the audio rendering of other content. Neither invisible nor silent content is
considered rendered content.

In this document, the term "repair content" refers to
content generated by the user agent in order to correct an error condition. "Repair text" refers to the text portion of repair content.
Some error conditions that may lead to the generation of repair content
include:

Missing resources for handling or rendering content (e.g., the user agent
lacks a font family to display some characters, or the user agent does not
implement a particular scripting language).

This document does not require user agents to include repair content in the
document object. Repair content
inserted in the document object should conform to the Web Content Accessibility
Guidelines 1.0 [WCAG10]. For more information
about repair techniques for Web content and software, refer to "Techniques for
Authoring Tool Accessibility Guidelines 1.0"
[ATAG10-TECHS].

In this document, the term "script" almost always refers
to a scripting (programming) language used to create dynamic Web content.
However, in guidelines referring to the written (natural) language of content,
the term "script" is used as in Unicode
[UNICODE] to mean "A collection of
symbols used to represent textual information in one or more writing
systems."

Information encoded in (programming) scripts may be
difficult for a user agent to recognize. For instance, a
user agent is not expected to recognize that, when executed, a script will
calculate a factorial. The user agent will be able to recognize some
information in a script by virtue of implementing the scripting language or a
known program library (e.g., the user agent is expected to recognize when a
script will open a viewport or retrieve a resource from the Web).

In this document, the term "selection" refers to a user
agent mechanism for identifying a (possibly empty) range of
content. Generally, user agents limit the
type of content that may be selected to text content (e.g., one or more
fragments of text). In some user agents, the value of the
selection is constrained by the structure
of the document tree.

On the screen, the selection may be highlighted in a variety of ways, including
through colors, fonts, graphics, and magnification. The selection may also be
highlighted when rendered as synthesized speech, for example through changes in
speech prosody. The dimensions of the rendered selection may exceed those of
the viewport.

The selection may be used for a variety of purposes, including for cut and
paste operations, to designate a specific element in a document for the
purposes of a query, and as an indication of point of regard.

The selection has state, i.e., it may be "set," programmatically or through
the user interface.

In this document, each viewport is expected to have at most one selection.
When several viewports coexist, at most one viewport's
selection responds to input events; this is called the current selection.

Note: Some user agents may also implement a selection for
designating a range of information in the user agent user interface.
The current document only includes requirements for a content
selection mechanism.

In this document, the expression "serial access" refers to
one-dimensional access to rendered content.
Some examples of serial access include listening to an audio stream or watching
a video (both of which involve one temporal dimension), or reading a series of
lines of braille one line at a time (one spatial dimension). Many users with
blindness have serial access to content rendered as audio, synthesized speech,
or lines of braille.

The expression "sequential navigation" refers to navigation through an
ordered set of items (e.g., the enabled elements in a document, a
sequence of lines or pages, or a sequence of menu options). Sequential
navigation implies that the user cannot skip directly from one member of the
set to another, in contrast to direct or structured navigation. Users with blindness or some
users with a physical disability may navigate content sequentially (e.g., by
navigating through links, one by one, in a graphical viewport with or without
the aid of an assistive technology). Sequential navigation is important to
users who cannot scan rendered content visually for context and also benefits
users unfamiliar with content. The increments of sequential navigation may be
determined by a number of factors, including element type (e.g., links only),
content structure (e.g., navigation from heading to heading), and the current
navigation context (e.g., having navigated to a table, allow navigation among
the table cells).

Users with serial access to content or who navigate sequentially may require
more time to access content than users who use direct or structured
navigation.

In this document, the terms "support," "implement," and "conform" all refer to what a developer has designed a user agent to do, but
they represent different degrees of specificity. A user agent "supports"
general classes of objects, such as "images" or "Japanese." A user agent "implements" a specification (e.g., the PNG and SVG image format specifications
or a particular scripting language), or an API (e.g.,
the DOM API) when it has been programmed to follow all or part of a
specification. A user agent "conforms to" a specification when it implements
the specification and satisfies its conformance criteria.

In this document, "to synchronize" refers to the act of
time-coordinating two or more presentation components (e.g., a
visual track with captions, or several
tracks in a multimedia presentation). For Web content developers, the
requirement to synchronize means to provide the data that will permit sensible
time-coordinated rendering by a user agent. For example, Web content developers
can ensure that the segments of caption text are neither too long nor too
short, and that they map to segments of the visual track that are appropriate
in length. For user agent developers, the requirement to synchronize means to
present the content in a sensible time-coordinated fashion under a wide range
of circumstances including technology constraints (e.g., small text-only
displays), user limitations (slow reading speeds, large font sizes, high need
for review or repeat functions), and content that is sub-optimal in terms of
accessibility.

A mechanism for encoding instructions to be rendered, played or executed by user agents. Web Content technologies may include markup languages, data formats, or programming languages that authors may use alone or in combination to create end-user experiences that range from static Web pages to multimedia presentations to dynamic Web applications. Some common examples of Web content technologies include HTML, CSS, SVG, PNG, PDF, Flash, and JavaScript.

As used in this document a "text element" adds
text characters to either
content or the user interface. Both in the Web
Content Accessibility Guidelines 1.0 [WCAG10] and in this document, text
elements are presumed to produce text that can be understood when rendered
visually, as synthesized speech, or as Braille. Such text elements benefit at
least these three groups of users:

visually-displayed text benefits users who are deaf and adept in reading
visually-displayed text;

synthesized speech benefits users who are blind and adept in use of
synthesized speech;

braille benefits users who are blind, and possibly deaf-blind, and adept at
reading braille.

A text element may consist of both text and non-text data. For instance, a
text element may contain markup for style (e.g., font size or color), structure
(e.g., heading levels), and other semantics. The essential function of the text
element should be retained even if style information happens to be lost in
rendering.

A user agent may have to process a text element in order to have access to
the text characters. For instance, a text element may consist of markup, it may
be encrypted or compressed, or it may include embedded text in a binary format
(e.g., JPEG).

"Text content" is content that is composed of one or more text elements. A "text equivalent" (whether in content or the user interface) is an
equivalent composed of one
or more text elements. Authors generally provide text equivalents for content
by using the alternative
content mechanisms of a specification.

A "non-text element" is an element (in content or the user interface) that
does not have the qualities of a text element. "Non-text content" is composed
of one or more non-text elements. A "non-text equivalent" (whether in content
or the user interface) is an equivalent
composed of one or more non-text elements.

In this document, a "text decoration" is any stylistic
effect that the user agent may apply to visually rendered text that does not affect the
layout of the document (i.e., does not require reformatting when applied or
removed). Text decoration mechanisms include underline, overline, and
strike-through.

A text transcript is a text equivalent of audio
information (e.g., an audio-only presentation or
the audio track of a movie or other
animation). It provides text for both spoken words and non-spoken sounds such
as sound effects. Text transcripts make audio information accessible to people
who have hearing disabilities and to people who cannot play the audio. Text
transcripts are usually created by hand but may be generated on the fly (e.g.,
by voice-to-text converters). See also the definitions of
captions and collated text
transcripts.

The software and documentation components that together,
conform to the requirements of this
document. This is the most common use of the term in this document and is the
usage in the guidelines.

Any software that retrieves and renders Web content for users. This may
include Web browsers, browser extensions, media players, plug-ins,
and other programs — including assistive technologies —
that help in retrieving and rendering Web content.

User agent default styles are style property
values applied in the absence of any author or user styles. Some markup
languages specify a default rendering for content in that markup language;
others do not. For example, XML 1.0
[XML] does not specify default styles
for XML documents. HTML 4
[HTML4] does not specify default
styles for HTML documents, but the CSS 2
[CSS2] specification suggests a
sample
default style sheet for HTML 4 based on current practice.

the user agent user
interface, i.e., the controls (e.g., menus, buttons, prompts, and
other components for input and output) and mechanisms (e.g., selection and
focus) provided by the user agent ("out of the box") that are not created by
content.

the "content user interface," i.e., the enabled elements that are part of
content, such as form controls, links, and applets.

The document distinguishes them only where required for clarity. For more
information, see the section on requirements for content, for user agent features, or both @@.

The term "user interface control" refers to a component of the user agent
user interface or the content user interface, distinguished where
necessary.

The user agent renders content through one or more
viewports. Viewports include windows, frames, pieces of paper, loudspeakers,
and virtual magnifying glasses. A viewport may contain another viewport (e.g.,
nested frames). User agent user interface
controls such as prompts, menus, and alerts are not viewports.

Graphical and tactile viewports have two spatial dimensions. A viewport may also have
temporal dimensions, for instance when audio, speech, animations, and movies
are rendered. When the dimensions (spatial or temporal) of rendered content
exceed the dimensions of the viewport, the user agent provides mechanisms such
as scroll bars and advance and rewind controls so that the user can access the
rendered content "outside" the viewport. Examples include: when the user can
only view a portion of a large document through a small graphical viewport, or
when audio content has already been played.

When several viewports coexist, only one has the current focus at a given moment. This
viewport is highlighted to make it stand out.

User agents may render the same content in a variety of ways; each rendering
is called a view. For instance, a user agent may allow users to view
an entire document or just a list of the document's headers. These are two
different views of the document.

"top-level" viewports are viewports that are not contained within other user agent viewports.

A visual object is content rendered through a graphical
viewport. Visual objects include graphics,
text, and visual portions of movies and other animations. A visual track is a
visual object that is intended as a whole or partial presentation. A visual
track does not necessarily correspond to a single physical object or software
object.

Appendix B: How to refer to UAAG 2.0 from other documents

Appendix C: References

For the latest version of any W3C specification please consult the list of W3C Technical Reports at http://www.w3.org/TR/. Some documents listed below may have been superseded since the publication of this document.

Note: In this document, bracketed labels such as "[WCAG20]" link to the corresponding entries in this section. These labels are also identified as references through markup.

Other previously active UAWG participants and other contributors to UAAG 2.0:

This publication has been funded in part with Federal funds from the U.S. Department of Education under contract number ED05CO0039. The content of this publication does not necessarily reflect the views or policies of the U.S. Department of Education, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.